1. Field of the Invention
The present invention relates to a data writing system capable of writing data in an electrically rewritable ROM (Read Only Memory) mounted on a target board such as a printed circuit board used, for example, as a facsimile control board.
2. Discussion of Background
As the electrically rewritable ROM, there are known, for example, EEPROM (Electric Erasable Programmable ROM) and flash memory, from which data written therein can be electrically erased and in which written data can be electrically rewritten.
Conventionally, when data is written in such a ROM, the ROM is attached to a ROM writer, without being mounted on a printed circuit board, that is, in the form of a single part, and when the data writing is finished, the data written ROM is mounted on a circuit board by soldering.
In such a data writing method, however, when the data written ROM is detached from the ROM writer, there is a risk that leads extending from the ROM are bent and improper soldering takes place.
In order to eliminate such a risk, in Japanese Laid-Open Patent Application No. 9-274798, there is proposed a method of writing program data in an electrically rewritable ROM mounted on a printed circuit board by use of a particular ROM writer. According to this method, after the ROM is mounted on the printed circuit board, the program data is written in the ROM, so that there is not the step of detaching the ROM from the ROM writer as in the above-mentioned conventional method and therefore, there is no risk that the leads thereof are bent.
However, in the data writing method proposed in Japanese Laid-Open Patent Application No. 9-274798, the ROM mounted printed circuit board is manually attached to the data writing unit for electrically connecting the ROM to the data writing unit by an operator, and this manual operation by the operator increases the production cost for writing program data in the ROM mounted on the printed circuit board.
It is therefore an object of the present invention to provide a data writing system capable of writing data in an electrically rewritable ROM (Read Only Memory) mounted on a target board, without the necessity for the operator who manually connects the ROM mounted on a printed circuit board to the data writing unit, thereby reducing the production cost of the data written ROM mounted on the target board, which can be used, for example, as a facsimile control printed circuit board.
The above object of the present invention can be achieved by a data writing system capable of writing data in at least one electrically rewritable ROM mounted on a target board, comprising:
a transportation unit for transporting the target board to a predetermined writing position at which data is to be written in the ROM,
a data writing unit for writing data in the ROM mounted on the target board, and
a connection unit for electrically connecting the ROM mounted on the target board at the predetermined writing position and the data writing unit through at least one transmission line extending from the ROM.
In the above data writing system, the ROM mounted on the target board is transported to a predetermined writing position by the transportation unit, and at the predetermined writing position, the ROM and the data writing unit are electrically connected through the connection unit, so that the data writing unit can write data in the ROM mounted on the target board through the connection unit.
Thus, according to the present invention, the connection operation can be automatically carried out by the connection unit without the necessity for the operator, in contrast to the conventional connection operation which is conducted manually by an operator.
The connection unit can be constructed either separately form the data writing unit or integrally with the data writing unit.
When the connection unit is constructed separately from the data writing unit, data writing can be carried out without changing the structure of the data writing unit by using a connection unit suitable for the kind of ROM employed and the position of the ROM on the target board.
In the above data writing system of the present invention, the connection unit may comprise a contact member which comes into contact with the transmission line extending from the ROM, so that through the contact member and the transmission line, the ROM can be electrically connected to the data writing unit.
In order to electrically connect the connection unit to the ROM mounted on the target board, for example, there can be devised a method of connecting a connector provided at the connection unit to a connector provided at the target board. This method, however, has the problems that high positional accuracy is required for the connectors in order to connect the two connectors, and high pressing force is also required for inserting one connector in another connector, which hinders smooth connection of the two connectors.
In order to eliminate the above problems, in the data writing system of the present invention, the contact member, which comes into contact with the transmission line extending from the ROM, is provided in the connection unit, whereby through the contact member and the transmission line, the ROM is electrically connected to the data writing unit. In this structure, the connection can be smoothly carried out without any substantial load.
The transmission line extending from the ROM, with which the contact member comes into contact, includes, for example, electric wires on the target board, extending from the ROM, leads of the ROM, and connector terminals provided on the target board.
In the above data writing system of the present invention, the connection unit may also comprise a plurality of contact members through which the connection unit is capable of electrically connecting to a plurality of connection points of the transmission line extending from the ROM, so that through the transmission line and the contact members, the ROM is electrically connected to the data writing unit.
When the contact member of the connection unit is electrically connected to the ROM mounted on the target board which has been transported to a predetermined position by the transportation unit, there is a risk that connection failure takes place between the contact member and the ROM. When such connection failure takes place, proper data writing cannot be carried out, so that the data writing has to be done over again. This will reduce the production efficiency.
In order to prevent this problem, in the data writing system of the present invention, the connection unit can comprise a plurality of contact members, so that the connection unit is electrically connected to a plurality of connection points of the same transmission line extending from the ROM, whereby the data to be written is transmitted from the data writing unit to the ROM mounted on the target board through a plurality of transmission routes. Therefore, even if some connection failure occurs in one transmission route between the connection unit and the ROM mounted on the target board and therefore data transmission becomes impossible through the transmission route, the data transmission to the ROM can be carried out through the other transmission routes. This will reduce the doing over the data transmission due to the above-mentioned connection failure.
In the above data writing system of the present invention, at least part of the plurality of the contact members may come into contact with the same transmission line from both sides, a front side and a back side, of the target board.
The above data writing system is constructed so as to cause the plurality of the contact members to come into contact with the same transmission line extending from the ROM from both sides of the target board. In other words, the contact members are disposed so as to hold the target board therebetween and come into contact with the same transmission line on the target board. In this structure, even if the contact members disposed on one side of the target board are not in proper contact with the transmission line due to the deposition of a flux or foreign materials thereon, the contact members on the other side of the target board can secure transmission routes to the transmission line, whereby there can be reduced the doing over the data transmission which is caused by the above-mentioned connection failure.
Furthermore, in the above-mentioned data writing system of the present invention, the connection unit may comprise:
a contact member which electrically comes into contact with the transmission line extending from the ROM,
a connection member which is electrically connected to the data writing unit, and
a substrate comprising a connection line through which the contact member and the connection member are electrically connected.
When a commercially available data writing unit for writing data in a single part ROM is connected to the ROM mounted on the target board, there may occur a problem that the power current supplied from the data writing unit to the target board becomes insufficient for writing data in the ROM mounted on the target board.
When such a commercially available data writing unit is used, a heavy drive load is applied to the data writing unit, so that there may occur a problem that normal data writing in the ROM cannot be carried out.
Therefore, in the above-mentioned data writing system of the present invention, the substrate is disposed between the ROM mounted on the target board and the data writing unit, whereby when the power current supplied to the target board becomes insufficient, or when the drive load on the data writing unit is excessively large, there can be provided circuits and electronic parts for solving these problems on the substrate. For instance, in order to reduce the drive load on the data writing unit, there can be provided a buffer in the transmission line between the data writing unit and the ROM.
In the data writing system of the present invention, the transportation unit may be constructed so as be capable of transporting a plurality of the target boards to each predetermined position thereof, whereby the connection unit can electrically connect the data writing unit and the ROM mounted on each target board transported to each predetermined position.
In this data writing system, data can be simultaneously written in at least one ROM mounted on each of a plurality of target boards by a single data writing operation.
Each of the plurality of the target boards may mount thereon the same ROMs or different ROMs.
When data writing is carried out in different ROMs, it is preferable that the ROMs have the same capacity. The positions of the ROMs mounted on each target may be different.